Adding a Processor, Using WinMondems
When I add another processor will Linux automatically use it, or do I need to do something else?
Saturday, September 15th, 2001
When I add another processor will Linux automatically use it, or do I need to do something else?
In short, it depends. Linux can support the use of multiple processors directly in the kernel, but whether you have this compiled into your kernel is really the question at hand.
Use of multiple processors under Linux is supported via Symmetrical Multi-Processing. SMP allows Linux to pass threads to the various CPUs on the machine in a hopefully equal manner, allowing for machine tasks to be performed quickly. This has a number of noticeable side effects.
First of all, your kernel messages at boot time will be altered to represent the two processors now living in the machine. Secondly, /proc/cpuinfo will now present you with two (or more) processors on its lists. However, the first really quirky thing that you will come across will be the process load identifiers.
The machine load will still be calculated in a similar manner; however, it is only when the machine reaches a load of 2.0 (or n.0, where n is a number of processors) that the number of queued processors exceeded the number of available CPUs.
Listing One: dmesg Output |
